Varying Chain Tension

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r00t4rd3d

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Aug 2, 2010
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Having a weird issue. When I spin my rear tire my drive chain at some points is loose and has 3/4 inch slack another half turn its super tight with almost no slack.

Your first idea was also mine. The sprocket is not centered on my hub , right ? Wrong.

I measured with a tape measure , did the string method then finally I made a jig to hold a screw driver to actually see if it was not centered while the wheel was spinning. Its practically dead nuts. I marked my sprocket with a marker 12 & 6 and 9 & 3 o'clock Im not off more then a 1/16 an inch any way.

My tire and sprocket are both true the other way too , left to right.

On the compression stroke do these engines have more torque on the counter sprocket or something ? I got the 80 BGF special off ebay.

What am I missing ?

:/
 
Last edited:

Mac

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Dec 3, 2009
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new sprocket?? Is the chain riding up on the sprocket? Sometimes, the sprocket needs to be "dressed" a bit, so it seats evenly IN the teeth, just a thought.
 

2door

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Sep 15, 2008
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new sprocket?? Is the chain riding up on the sprocket? Sometimes, the sprocket needs to be "dressed" a bit, so it seats evenly IN the teeth, just a thought.
This is my thoughts too. Either that or the chain has tight spots that aren't allowing it to follow the sprocket teeth. Check as you slowly rotate the rear wheel, clutch disengaged, and see if the chain is staying the same depth in the sprocket teeth. I like to use a 3-M metal finishing pad on the sprocket before installing it to smooth the teeth and take off any rough areas. If the problem is in the chain replace it with a good quality induatrial #41 chain.

Tom
 

Venice Motor Bikes

Custom Builder / Dealer/Los Angeles
Mar 20, 2008
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It doesn't take the sprocket being off by much to make the chain do what yours is doing!

Also, the tips of the sprocket teeth can be different that the valleys of the sprocket where the chain rides! ;)
 

fat daddy

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Jun 14, 2010
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I have a Cranbrook that I bought at Wallyworld about 2 months ago and I had a MM set up on it,and it worked.
 

KCvale

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Feb 28, 2010
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Does anyone know if that would fit a Cranbrook wheel ? I dont have a proper way to measure the hub.
That is pretty cool hub mount sprocket setup!
That would sure be easier and better than spoke mounts.
It just costs more than your whole bike.
Bummer.

I don't know if Gurbee sells just parts for their bicycle designed for motorizing or not, if so you would be off just buy a whole new Grubee GT1 back wheel.
It's a quality wheel with a hub mounted sprocket on it.

The whole bike is only $300 so just a back wheel would have be less that $100 if they sell them.

I have to go with these guys suggestion though.
The sprocket may be centered but has poor teeth, or you have some tight chain links, the tight links really show up going around the small front sprocket where they have to pivot a lot.
 

r00t4rd3d

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That is pretty cool hub mount sprocket setup!
That would sure be easier and better than spoke mounts.
It just costs more than your whole bike.
Bummer.
Its only $59 bucks ? And I think the guy that owns that site , Jim , is a forum member here and gives discounts to other forum members ? I swear I seen that somewhere.
 

gcruiser

New Member
Jul 27, 2010
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Check out livefastmotors.com and get the spring loaded chain tensioner. I put one on my bike as well as the clamshell(small) sprocket mount and all my chain jumping/slipping off issues went away! it also takes a little careful adjustment of the rear wheel to make sure the sprockets are aligned, clearing the drive chain,etc... every bike is different. took a bit of time for me to get it right, but it will get there!
 

KCvale

Well-Known Member
Feb 28, 2010
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Its only $59 bucks ? And I think the guy that owns that site , Jim , is a forum member here and gives discounts to other forum members ? I swear I seen that somewhere.
It is not $59 to get it to you, and Cranbrooks are like $85 right?
It would properly solve your problem however.

Call me the 'Anti-Drive Chain Tensioner Nazi' if you want, but I will say this every time I see it.
If a drive chain tensioner were a good thing motorcycles would have them.
Other than frame routing issues they are a BAD thing to add to the drive train.
They are a useless problem prone moving part on something that is always moving if the bike is.

I am sorry guys, but the entire concept of putting some variable tensioner on the drive side to compensate for a lousy mount of some sort just really rubs my logic the wrong way!

You don't fix a problem by adding another to it.
I have NEVER had to use a tensioner on the drive side, and only two builds couldn't be chain matched and got a pedal side one.

Please, just give that some thought, especially those of you recommending them.
Thanks ;-}
 
Sep 20, 2008
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Clearwater, FL
web.tampabay.rr.com
It is not $59 to get it to you, and Cranbrooks are like $85 right?
It would properly solve your problem however.

Call me the 'Anti-Drive Chain Tensioner Nazi' if you want, but I will say this every time I see it.
If a drive chain tensioner were a good thing motorcycles would have them.
Other than frame routing issues they are a BAD thing to add to the drive train.
They are a useless problem prone moving part on something that is always moving if the bike is.

I am sorry guys, but the entire concept of putting some variable tensioner on the drive side to compensate for a lousy mount of some sort just really rubs my logic the wrong way!

You don't fix a problem by adding another to it.
I have NEVER had to use a tensioner on the drive side, and only two builds couldn't be chain matched and got a pedal side one.

Please, just give that some thought, especially those of you recommending them.
Thanks ;-}
KC,

Click on the link below and have a look at post #29. You'll get a laugh. ;)

http://motorbicycling.com/f3/im-confused-about-all-chain-tensioner-12585-3.html

Jim
 
Sep 20, 2008
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Clearwater, FL
web.tampabay.rr.com
Did MM leave pirate and go to piston bikes?
Corgi,

No we didn't bail out on Pirate Cycles. I've been working with Justin for a year and a half...he has a solid retail business that offers the customer service benefits that consumers have come to expect in a retail enviornment.

Piston Bikes enquired about becoming a dealer several months ago. After a few conversations with Robert I decided they were a good fit too. I was right!

I'm very happy to have both, Pirate Cycles & Piston Bikes, as distributors for my products.

Jim
 

r00t4rd3d

New Member
Aug 2, 2010
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Well I got a sprocket adapter and while installing it I noticed 1 tooth on my sprocket that was bent. I installed the adapter , straightened the tooth and my varying chain tension is gone.

:)